A person familiar with the negotiations for the new series told TheWrap that all of the cast from "X-Men: First Class" are contracted to return to the sequel.

Last month, Singer announced that Patrick Stewart and Ian McKellen would be joining the film.

In late November, Singer also tweeted: "I'd like to officially welcome back James McAvoy, Jennifer Lawrence, Michael Fassbender and Nicholas Hoult to 'X-Men: Days of Future Past.'" Fox is aiming to release the film on July 18, 2014. Singer was originally slated to serve as a producer on the film, alongside Lauren Shuler Donner and Simon Kinberg.